The Lakeside Greenbelt Trail is a great wooded path that winds around the canyon gullies leading out towards views of Lake Travis and the farther out Peninsula Pass Trail
, from which you can get down to the lake itself for a dip or a nice photo op.
Along the way, you'll have three creek crossings and plenty of 'interval workout' sections as you are pretty much going up and down the midsections of the canyons before you come to the crossing with the Peninsula Pass Trail
The trailhead is clearly marked with a sign and begins on the lake side of the Rough Hollow Bridge. Note that 'Rough Hollow' is a community within the City of Lakeway.
There are two ways I would recommend you start this trail:
Way 1: Find parking at the Rough Hollow Info Center just up the road from the bridge (towards Hwy 71), and then ride back to the bridge trailhead using the sidewalk access.
Way 2: Do this trail as a segment of a larger ride starting from the Lakeway Canyonlands and using the Rough Hollow Trail Connector
to reach the trail.